ES2728411T3 - Closing element for a borescope opening of a gas turbine - Google Patents

Abstract

Gas turbine, especially aircraft gas turbine, with at least one turbine stage and annular channel (10) conducting hot gas associated with the gas turbine stage, and with at least one compressor stage and annular channel conducting hot gas associated with the compressor stage, wherein the annular channel (10) of the gas turbine stage has a radial outer wall (12) in which at least one borescope opening (18) is provided, in wherein the borescope opening (18) has an opening edge (20, 20a, 20b) built into the outer wall (12), which opening edge is connected to an opening wall (22) to the outside, preferably substantially in the radial direction (RR), wherein a closing element (24) is inserted into the borescope opening (18), the closing element (24) having a main area (26) and a closing area (28). ) joined with the main area (26), where the closing area (28) is surrounded by the pa opening net (22), where the closing zone (28), by reference to a longitudinal axis (LA) of the closing element (24) is constructed symmetrical to rotation, at least partially, where the diameter ( DM) of the closure zone (28) essentially corresponds to the inner diameter (MD) of the borescope opening (18) formed in the opening wall (22), and where the closure zone (28) is dimensioned so which, acting together with the opening wall (22), seals the hot gas channel (10) because its outer surface is in contact with the opening wall (22), characterized in that the closing area (28) is constructed sphere-shaped and in that the closure element (24) is dimensioned such that the closure zone (28), in a state inserted into the borescope opening (18), partially protrudes over the opening edge (20, 20a). , 20b) inner radial of the borescope opening (18) and with it is partially introduced into the ca hot end (10).

Description

DESCRIPTION

Closing element for a borescope opening of a gas turbine

The present invention relates to a closing element for a borescope opening of a gas turbine, especially an airplane gas turbine, wherein the borescope opening has an inner radial opening edge oriented towards an annular channel of the turbine of gas that conducts gas, where the closing element has a main zone and a closing zone connected to the main zone, and where the closing zone referred to a longitudinal axis of the closing element is at least partially constructed, symmetrical to rotation.

The address data, such as "Axial-" or "axial", "Radial-" or "radial" and "circumferential-" must be understood primarily referring to the machine axis of the gas turbine as long as the context does not come off explicitly or implicitly something else.

These types of closure elements, which can also be referred to as borescope plugs, are already known. Generally, such borescope plugs are screwed in by means of a thread, where the symmetrically closed area of rotation, generally spherical, closes tangentially with an inner contour of the annular channel. Due to this arrangement of the closing element, which with its closing zone is almost sunk in the borescope opening or in the inner contour of the annular channel, large intermediate spaces are produced between the outer contour of the closing zone and a wall that Limits the borescope opening, which lead to disturbances in the hot gas stream. An example of this is published in document CN 202994 190 U.

It is the mission of the invention to develop a closing element of a gas turbine so that the aforementioned disadvantages can be reduced.

This mission will be solved according to the invention, by a gas turbine according to the characteristics of claim 1.

It is then proposed that the closure element has a spherical shaped closure zone and is sized in such a way that the closure zone in a state introduced into the borescope opening partially protrudes over the inner radial edge of the borescope opening.

It has been shown that when the closure zone protrudes above the borescope opening or within the annular channel, it leads to the borescope opening being better filled by the closure zone, so that the dimensions of the disadvantageous intermediate spaces. This has surprisingly shown that when the closure zone protrudes in the annular channel, especially due to the symmetrical design of the closure zone rotation, it acts less disturbing the current than the existence of large intermediate spaces in the case of zone of closing that close tangentially with the inner contour of the annular channel.

So that a closing element such as this can be introduced independently of its angular mounting position referred to the inner contour of the annular channel, the closing zone can be constructed for example also in the form of a cone or in the form of a cone trunk.

For this, the closure zone is sized in such a way that, in conjunction with an opening wall that joins the inner radial edge, the annular channel that conducts the hot gas seals.

For this, it is necessary that the maximum diameter of the closing area corresponds to the diameter of the borescope opening formed by the opening wall. In the case of the spherically constructed closure zone the maximum diameter of the closure zone is equal to the maximum diameter of the corresponding sphere. In the case of a closure zone constructed as an example in the form of a cone or in the form of a cone trunk, the maximum diameter of the closure zone is the largest diameter of the cone or cone trunk.

Preferably the main zone has a length that is measured in such a way that the closing zone determined in its dimensions depending on the inside diameter of the borescope opening protrudes from the inner radial opening edge at a value corresponding to at least 2% of the diameter of the sphere.

The outer wall of the annular channel may be inclined with respect to the axial direction of the gas turbine, at least in sections, so that the outer wall essentially has the shape of an enveloping surface of a cone trunk. Special mention is made here that the outer wall of the annular channel is not stamped in a straight or linear line for its entire axial length, as in the case of the envelope line of a commonly defined cone, but that the envelope surface may also be Built slightly wavy.

In the development it is proposed that the closing zone referred to an axial longitudinal section protrudes in the annular channel through the borescope opening above an imaginary line that joins an axial leading edge zone and an axial rear edge area of the opening edge along the inclined enveloping surface in axial direction. This imaginary junction line can also be understood as that line that according to the state of the art has formed a tangent to the closing zone when the closing zone is almost sunk in the borescope opening or has been tangentially closed with the inner contour of the annular channel

So that the hot gas stream is only minimally disturbed by the closure zone that protrudes in the annular channel, it is preferred that the closure zone protrudes in the annular channel by a measured distance orthogonal to the imaginary line, where the distance is approximately 2% to 30%, preferably 10% to 24%, most preferably 14% to 18% of the diameter of the borescope opening measured in the axial direction. In other words, the distance that protrudes in the annular channel must be no more than about 2% to 30% of the diameter of a sphere-shaped closure element whose outer diameter, generally, essentially corresponds to the inner diameter of the borescope opening

According to the invention, a spherical segment of the closure zone protrudes in the annular channel. Then, the height of the spherical segment can correspond to the distance measured in orthogonal.

The invention will now be described by reference to the accompanying examples by way of example and not limitation.

Fig. 1 shows a schematic and simplified longitudinal section representation of an extract of a turbine stage of a gas turbine according to the invention with a closure element for a borescope opening inserted therein.

Fig. 2 shows, in partial figures A) and B) two enlarged representations of the area named with II in figure 1, where in figure 2A) additionally a closing zone is indicated in a known position, and where in figure 2B) another position of the closing zone according to the invention is shown.

Figure 1 shows a partial representation of an annular channel 10 that conducts hot gas from a turbine stage not shown in detail from a gas turbine not equally shown in detail. The axial direction referred to the machine axis of the gas turbine is called AR and the radial direction is called RR.

The annular channel 10 is limited at least by zones, by an annular channel wall 12 with an inner face 14 oriented towards the hot gas. The annular channel wall 12 is connected with other components of the turbine stage or the gas turbine that are not described in detail, especially a housing component 16. In order to inspect an affected turbine stage, especially its mobile blades, a borescope opening 18 is provided in the turbine channel wall 18. The corresponding accesses are usually provided, approximately in the housing component 16 and, where appropriate, other Gas turbine modules located radially further outward, so that a borescope can be introduced through these accesses and the borescope opening 18 into the annular channel wall 12 and the turbine stage can be examined.

The annular channel 10 has an outline corresponding to the inner face 14, where the inner face 14 runs inclined towards the axial direction AR. The inner face 14 of the annular channel 10 has essentially, easily said, the shape of an envelope surface of a cone, where as can be seen in Figure 1, the inner face 14 is not stamped as a straight or linear line in all its length, like the envelope line of a commonly defined cone. In other words, it can also be said that along the axial direction AR, which essentially corresponds to the direction of circulation of the hot gas, the annular channel widens in the radial direction RR. In this inner face 14, which is usually also curved in a circumferential direction around the machine axis, the borescope opening 18 is inserted, where in transition, between the borescope opening 18 and the inner face 14, an edge of opening 20 located radially inside. In the radial direction r R, the opening edge 20 is joined by an opening wall 22 of the borescope opening 18. This opening wall 22 is constructed in the wall 12 of the annular channel. During operation of the gas turbine, the borescope opening 18 is closed by a closing element 24 which can also be called a borescope cap. Essentially, the closing element 24 is formed by a main zone 26 and a closing zone 28 that are connected to each other, especially constructed from one piece to another. The closure zone 28 is usually constructed symmetrical to the rotation about an axis of rotation, which in the present embodiment corresponds to the longitudinal axis LA of the closure element 24. In the example shown the closure element 24 is placed in the turbine stage or in the gas turbine such that the longitudinal axis LA extends essentially parallel to the radial direction RR. You can really think of other mounting positions in which the longitudinal axis is inclined with respect to the radial direction RR, axially forward or axially backward. In addition, the longitudinal axis LA can also deviate from the radial direction RR in the circumferential direction. Using a closing element 24 symmetrical to the rotation in the form of a sphere or for example of a cone, the same closing element 24 can be used in different mounting positions.

In the embodiment shown in Figure 1, the closing area 28 is constructed in the form of a sphere. In addition, the closure element 24 is designed in such a way that in a state inserted into the borescope opening 18 it protrudes with its closure zone 28 in the annular channel 10 or partially penetrates it. In the example shown, the closing zone 28 protrudes beyond an imaginary connecting line VL which (in axial direction AR) joins the front opening edge 20a and the rear opening edge area 20b with one another. In the sectional representation of FIG. 1, this connection line VL can be seen as the imaginary complement of the inner face 14 of the annular channel wall if no borescope opening 18 is provided. Likewise, the connection line VL is inclined towards the radial direction RR and towards the axial direction AR. The closure zone 28 protrudes with its outer surface 30 in the annular channel 10, a distance AB that is measured orthogonal to the connecting line VL, so that the closure zone protrudes beyond the opening edge 20 of the opening of borescope 18 located radially in inside. In this position, the closing area 28 comes into contact with its outer surface 30 with the opening wall 22 so that a sealing of the annular channel 10 of the turbine stage can be obtained.

Figure 2A shows an enlarged extract corresponding to zone II shown surrounded by dotted line of figure 1. Also in figure 2A is the closure zone 28 represented in its position inserted in the borescope opening 18. With line A dotted area 28a is shown which is inserted into the borescope opening 18 in a position known to the state of the art. In it, the closing area 28a with the inner face 14 or the contour of the annular channel 10 closes in such a way that the connecting line VL forms a tangent to the outer surface 30a of the closing area 28a. The closing area 28a is almost buried in the borescope opening.

In the case of the position of the closure element 28 so that it protrudes in the annular channel 10, an intermediate space 32 (single scratched surface) formed between the outer surface 30 and the opening wall 22, is reduced compared to the known position of the closure element 28a shown scratched in which the intermediate space 32 is larger in the zone 32a (scratched surface with crossed lines) or a corresponding volume. In addition, in the known arrangement of the closure element 28a an additional intermediate space 32b is also formed on the rear face of the closure area 28a in the direction of movement.

Due to the reduction of the intermediate space 32, the disturbances in the hot gas stream can be reduced, especially the turbulence in the intermediate space 32. Due to the symmetrical construction of the sphere-shaped rotation of the closure element 32 the part of The closing area that projects in the annular channel 10 can be surrounded with less resistance. The reduction of the intermediate space 32, especially in the volume in zones 32a and 32b in combination with the protrusion of the closure zone 32 in the annular channel 10 leads to minor disturbances of the hot gas stream, so that together You can get improved service and improved performance of the turbine stage.

In Figure 2A it can also be seen that for the modified position of the closure element 24 in the borescope opening 18, no adjustment is necessary in the sphere-shaped closure area 28, symmetrical to the rotation, but for example, the main section 26 is prolonged by an HL value compared to the known closure element. The extension HL of the main section 26 can be carried out in any position along the longitudinal axis LA. Correspondingly, the proposed solution can be used in existing gas turbines, because the shorter existing closing elements can be replaced by new, longer 24 closing elements.

Figure 2B shows in a representation of points, another position of the closing zone 28, so that it protrudes even more in the annular channel 10 (distance AB '), but precisely with its outer surface 30 comes into contact with the edge of rear axial opening 20b of the borescope opening 18. As described above by reference to Figure 2A, also in this case the main area 26 can be extended with respect to a main area 26 according to Figure 1 or 2A, in a value h L '. The intermediate space 32 has become smaller in the area or the volume 32c (of points with crossed lines), where the distance AB 'has become somewhat larger. The remaining identification symbols contained in Figure 2B identify components equal to those already described by reference to Figures 1 and 2A and are again contained in Figure 2B, even if they are not described again.

The distance AB between the imaginary joint line and the outer surface 30 of the closure zone, drawn in Figures 1, 2A and 2B is about 2% to 30% of the DM diameter of the borescope opening 18. Expressed from another Thus, the distance AB is about 2% to 30% of the diameter DM of the sphere-shaped closure zone 24. Preferred larger areas of distance AB are approximately 10-24% and also 14-18% of the DM diameter. Depending on the alignment and geometry of the borescope opening as well as the contour of the annular channel 10, it is possible to choose that the closing area 28 protrudes in the distance AB inside the annular channel 10, so that together it can be obtained a stream of hot gas with less disturbance, where the intermediate spaces 32, 32a, 32b between the closing area 28 and the opening wall 22 are minimized by increasing the separation AB of the outer surface 30 of the joint line VL

Overall, by means of the closure element 24 proposed for a borescope opening 18, the possibility of improving the circulation ratios in an annular channel 10 of a turbine stage is obtained, where contrary to the current teaching, it can be accepted that the closing zone protrudes inside the annular channel because this leads to a much smaller disturbance of the current, especially when a sphere-shaped closing zone is used.

List of identification symbols.

10 annular channel

12 annular channel wall

14 inside face

16 housing component

18 borescope opening

20 opening edge

20a front axial opening edge zone 20b rear axial opening edge zone 22 opening wall

24 closure element (borescope cap) 26 main zone

28 closing zone

30 outer surface

32 intermediate space

32nd increase in intermediate space

32b intermediate space

32c reduction of intermediate space

AB distance

AR axial direction

DM diameter

HL prolongation of main zone

THE longitudinal axis

RR radial direction

SR current direction

VL union line

Claims (6)

1. Gas turbine, especially aircraft gas turbine, with at least one turbine stage and an annular channel (10) that conducts hot gas associated with the gas turbine stage, and with at least one compressor stage and one annular channel that conducts hot gas associated with the compressor stage, wherein the annular channel (10) of the gas turbine stage has a radial outer wall (12) in which at least one borescope opening (18) is provided. , wherein the borescope opening (18) has an opening edge (20, 20a, 20b) constructed in the outer wall (12), opening edge to which an opening wall (22) is connected to the outside, preferably essentially in the radial direction (RR), where a closing element (24) is inserted into the borescope opening (18), where the closing element (24) has a main area (26) and a closing area (28) linked to the main zone (26), where the closing zone (28) is surrounded a by the opening wall (22), where the closing area (28), by reference to a longitudinal axis (LA) of the closing element (24) is constructed symmetrical to the rotation, at least partially, where the diameter (DM) of the closure zone (28) essentially corresponds to the internal diameter (DM) of the borescope opening (18) formed in the opening wall (22), and where the closure zone (28) is sized so that acting together with the opening wall (22) seals the hot gas channel (10) because with its outer surface it is in contact with the opening wall (22), characterized in that the closing area (28 ) is constructed in the form of a sphere and because the closing element (24) is sized so that the closing area (28), in a state introduced into the borescope opening (18), partially protrudes over the opening edge ( 20, 20a, 20b) radial interior of the borescope opening (18) and with it p essentially in the hot runner (10). 2. A gas turbine according to claim 1, characterized in that the main area (26) has a length that is measured so that the closing area (28) in a state inserted in the borescope opening (18) protrudes over the edge opening (20, 20a, 20b) radial inside and really in an amount that at least corresponds to 2% of the diameter (DM) of the closing area (28). 3. Gas turbine according to claim 1 or 2, characterized in that the outer wall (12) of the annular channel (10) is inclined, at least by zones, by reference to the axial direction (Ar) of the gas turbine of such that the outer wall (12) essentially has the shape of an enveloping surface of a cone trunk. 4. A gas turbine according to claim 3, characterized in that the closing zone (28) through the borescope opening (18) protrudes in the annular channel (10) above an imaginary line (VL) that joins a front axial opening edge zone (20a) of the opening edge (20) and a rear radial opening edge area (20b) of the opening edge (20) along the enveloping surface inclined towards the axial direction (AR ). 5. Gas turbine according to claim 4, characterized in that the closing zone (28) protrudes in the annular channel (10) by a distance (AB) measured orthogonally to an imaginary line (VL), wherein the distance (AB ) is about 2% to 30%, preferably 10% to 24%, especially 14% to 18% of the inside diameter (DM) of the borescope opening (18) measured in the axial direction (AR). 6. Gas turbine according to claim 5, characterized in that the height of the sphere segment with which the sphere-shaped closure area (28) protrudes in the annular channel (10), measured from the imaginary line (VL), corresponds to the distance (AB) measured in orthogonal.